The present invention relates to so-called Universal Serial Bus interconnects, in general, and to Universal Serial Bus hubs in which cabling is simplified, in particular.
The Universal Serial Bus (xe2x80x9cUSBxe2x80x9d) development as a standard for use with personal computers has been motivated by the necessity to provide for connection of the personal computer (xe2x80x9cPCxe2x80x9d) to the telephone, the necessity for ease-of-use or the so called xe2x80x9cplug and playxe2x80x9d approach, and the need to facilitate the addition of external peripherals. For years, computer users have been limited in their ability to add devices to their computers.
The Universal Serial Bus of xe2x80x9cUSBxe2x80x9d is a standard peripheral interface for attaching PCs to a wide variety of peripheral devices including keyboards, mice, scanners, printers, game controllers, modems and other peripherals. With USB, up to 128 devices may be interconnected.
All types of devices are now available as USB devices. No longer does a user have to worry about configuring his/her system. When a USB device is plugged in, the device is automatically detected, and the software is automatically configured. The USB is useable with video capture devices, keyboards, mice and scanners. USB devices require a central processing unit as a host unit.
The standards for USB are publicly available and are the result of a collaborative effort by major computer manufacturers. The Universal Serial Bus Specification revision 1.1 (Sep. 23, 1998) by Compaq, Intel, Microsoft and NEC sets forth connectivity standards for PC architecture. It sets forth a xe2x80x9cfast, bi-directional, isochronous, low-cost, dynamically attachable serial interface structure that is consistent with the requirements of the PC platform of today and tomorrow.xe2x80x9d The specification defines an industry-standard USB and describes the bus attributes, the protocol definition, types of transactions, bus management, and the programming interface required to design and build systems and peripherals that are compliant with the standard. All USB devices connect to the USB through ports on specialized USB devices referred to as xe2x80x9chubsxe2x80x9d. Hubs are wiring concentrators. Attachment points to hubs are referred to as ports. Each hub converts a single attachment point into multiple ports. The architecture supports concatenation of multiple hubs.
The USB topology is such that the USB connects USB devices with a USB host in a tiered star topology. A hub is at the center of each star. Each wire segment of the USB is a point-to-point connection between the host and a hub or function, or a hub connected to another hub or function. The upstream port of a hub connects towards the host. Each downstream port of a hub allows connection to another hub or function.
In the USB topology there is only one host. A root hub is integrated within the host system to provide one or more attachment points. Additional attachment points to the USB are provided by hubs. Each hub may be connected to additional hubs and to functions which provide capabilities to the system, such as an ISDN connection, a digital joystick or speakers. All USB devices attach to the USB through ports on hubs.
The USB transfers signal and power over a four wire cable. All USB devices have an upstream connection, and USB cables have an upstream and a downstream connector. The upstream and downstream connectors are not mechanically interchangeable to eliminate illegal loopback connections at the hubs.
In accordance with USB standards, all attached devices connect to the host device through a single connector type using a tiered star topology. Personal computers typically have one or two USB ports. To provide for connecting to a number of devices, a cable connection is provided to a USB hub via a USB cable. Currently, hubs having four or seven ports are dominant, which give four or seven additional USB connectors. In addition, a USB cable may connect from the USB hub to one or more additional USB hubs. One of the limitations that applies to USB architecture is a distance limitation which is a 5 meter cable length, or its electrical equivalent, between devices.
A PC configuration using USB hubs and function,s will require a number of different items to be cabled together. The cables interconnecting the hubs and functions creates an undesirable cabling appearance.
In accordance with the principles of the invention, a docking station for a universal serial bus includes a hub having an upstream connector and a plurality of downstream connectors. The hub is disposed generally in a horizontal plane. A docking housing is coupled to the hub. The docking housing receives at least one USB module. The docking housing carries a first connector that is electrically coupled to the hub. The module carries a mating first connector configured to electrically connect to the first connector when the module is inserted into the docking housing. When the module is so inserted, the module is automatically connected to the hub without use of a separate cable. Further in accordance with the invention, additional modules may be inserted into the docking station. In the illustrative embodiment, the docking station can accommodate up to three modules. The three modules may be any combination of USB hubs and USB functions.
Further in accordance with the invention, a USB module may be used as a stand alone unit with a removable sleeve that snapingly engages the module. The USB module includes a housing containing USB interfacing circuitry. A connector is disposed on the rear of the housing, and one or more first retaining elements are carried on the housing. The sleeve adapted to cover a portion of said housing has one or more second retaining elements adapted to engage corresponding ones of the first retaining elements, whereby the sleeve is removably retained on the USB module housing.
Further in accordance with the invention, a USB connector is provided which has an elongated sleeve and a plurality of electrical contacts carried therein. A plurality of electrical connector pins extend from said sleeve in and parallel with a longitudinal axis of the sleeve. A pair of retainer arms or clips extend from the sleeve in a direction generally parallel to the longitudinal axis. Each retainer arm is of the same metal material as the sleeve and has a portion bent angularly such that when said connector is mounted onto a circuit board, the retainer arms exert retaining forces against said circuit board to retain the connector, thereby facilitating assembly. A shoulder disposed on the sleeve proximate the retainer arms provides surfaces that may be captured between a circuit board and a retainer plate disposed parallel to said circuit board.